Tankless water heater

ABSTRACT

This invention is including a controller, a waterway and a heat pump circulation loop; the waterway, in the water-flowing direction, successively includes: an inlet, a heating part and an outlet; the heat pump circulation loop successively includes: a compressor, an evaporator, a condenser and a throttle device, wherein the compressor is in control connection with the controller, and the condenser includes a heating condenser and a pressure relief condenser, wherein the heating condenser is in heat conduction contact with the heating part in the waterway and is set in series with the pressure relief condenser in the heat pump circulation loop, besides, a heating condenser valve is set in the branch where the heating condenser lies and a pressure relief condenser valve in that where the pressure relief condenser stands, wherein the heating condenser valve and the pressure relief condenser valve are in control connection with the controller.

TECHNICAL FIELD

The present invention relates to a tankless water heater, and more especially, to a heat pump-heated water heater.

DESCRIPTION OF THE RELATED ART

Usually, a tankless water heater is also named instantaneous or fast-heating water heater, characterized in that: cold water enters and hot water goes out, for which as along as the outlet valve is opened, hot water can be supplied continuously in a short period, and if not demanding hot water, just close the outlet valve to cut off the waterway and the heating will be suspended within a short time. At present, most tankless water heaters are electric heated and gas fuelled.

The principle of an electric-heated tankless water heater is to use a high-power electric heater to heat the cold water flowing through the heating area up to the predetermined service temperature quickly, so as to achieve the purpose of “cold water in and hot water out”. Since the water storage device on a thermal storage water heater is cancelled (for example, the water storage device of household electric water heaters generally holds water up to dozens of litres), the heater boasts small size and easy installation. Moreover, since it is unnecessary to heat the stored water in the storage device up to a certain temperature, the water consumption is not subject to the water storage capacity and the temperature and the water is available whenever necessary. The present water heater, compared with a thermal storage water heater, is far more convenient, and due to the characteristic of availability at any time, there is no need to heat the stored water and keep the temperature, which greatly saves energy consumption and is more energy-saving and environment-friendly.

However, since electric-heated tankless water heaters require high power, in some circuit environments, it does not meet the installation requirements, and for the characteristics of electric heating, the heat conversion efficiency is also unsatisfactory.

Gas-fuelled tankless water heaters are widely used as well, but the fuel gases (natural gas, liquid petroleum gas, or water gas, etc.) used accordingly are non-renewable energies, which cause the waste of valuable natural resources. Besides, due to insufficient combustion and other causes, this kind of water heater may lead to risks like CO poisoning.

Air-energy water heaters, also named air-source heat pump water heaters, are a type of water heater suddenly springing up over recent years, with the principle of absorbing low-temperature heat energy in the air by means of the refrigerant in the heat pump of the water heater and transferring the energy into high-temperature heat energy after compression of the compressor, so as to heat the water up. Due to the heating method of heat transfer via heat pump, this water heater features high efficiency and energy savings. It is reported that the energy-saving effect is 4 times that of an electric water heater and 3 times that of a gas-fuelled water heater.

The air-source heat pump heating system applied to the existing air-energy water heater generally consists of three parts, namely the main engine, the water tank, and the heating system; for a household water tank, first, water tanks with a general capacity of 150 to 320 L will occupy a very large part of the building area when being installed, and even if some are mounted outside the wall with supports, due to the weight of the tank itself and the water added in, this installation method is quite dangerous; second, as to the material and technology for the tank liner, no matter whether it is stainless or enamelled, owing to the deficiency of the manufacturing technology, tank leakage cannot be avoided; third, the heat exchanger in the tank is generally made of copper tubing or stainless steel tubing, which in the areas with inferior water quality may be corroded and perforated, leading to refrigerant leakage, which will be fatal for the unit; fourth, since the main engine and the water tank are required to be connected mutually with connecting tubes, it is very difficult to avoid human-made refrigerant leakage in installation; fifth, due to the characteristics of water-storage-type heat pump, it is required to provide a long period to heat the water up to a higher temperature, which cannot satisfy the requirement of instant water supply, besides, in the later period, the water temperature fluctuates significantly, which may affect the comfort of water use; in addition, since the level of condensation temperature determines the energy consumption of the unit, long-term operation under high condensation temperature and pressure of traditional unit with water tank will be a great challenge to the service life of compressor; sixth, if taking storage-type water tank, it is generally required to mix water when using water, which may cause several problems: 1) the hot water in the water tank is of low utilization rate; 2) during heat preservation, the water temperature of the water tank drops inevitably, which may increase energy consumption; 3) when installing water valve at the user's house, it is undoubtedly necessary to mount a water mixing valve, which may increase the material cost; seventh, generally, when the heat for the heating system comes from the water tank, it is required to install a heat exchange coil in the tank to form a closed circuit with floor heating coil or radiator and circulating water pump, which increases the difficulty of tank manufacturing technology and occupies water tank capacity.

Therefore, currently, various water heater solutions in the industry all have their own insurmountable principle defects.

BRIEF SUMMARY OF THE INVENTION

-   -   The present invention aims at providing a heat pump-heated         tankless water heater.

To realize the above purpose, the present invention provides a tankless water heater, including a controller, a waterway, and a heat pump circulation loop;

In the water-flowing direction, the waterway successively includes: an inlet, a heating part and an outlet;

The heat pump circulation loop successively includes: a compressor, an evaporator, a condenser and a throttle device, wherein the compressor is in control connection with the controller, and the condenser includes a heating condenser and a pressure relief condenser, wherein the heating condenser is in heat conduction contact with the heating part in the waterway and is set in series with the pressure relief condenser in the heat pump circulation loop, besides, a heating condenser valve is set in the branch where the heating condenser lies and a pressure relief condenser valve in that where the pressure relief condenser stands, wherein the heating condenser valve and the pressure relief condenser valve are in control connection with the controller;

The controller is used for controlling the opening and closing of the compressor, the heating condenser valve and the pressure relief condenser valve, specifically, when the water heater supplies hot water, keeping the heating condenser valve open; when requiring the closing of the compressor, judging whether the compressor running time is over the preset time, and if so, close the compressor; if not, close the heating condenser valve and open the pressure relief condenser valve, so as to enable the compressor to run till the preset time before closing it.

Wherein, the tankless water heater includes a fan, wherein the evaporator and the pressure relief condenser are located in the same air duct formed by the fan.

Wherein, the evaporator and the pressure relief condenser are in heat conduction connection via a radiator, for example, the evaporator and the pressure relief condenser are in wholly expanded connection through a copper tube-fin.

Wherein, the tankless water heater further includes an outflow water temperature sensor, which is connected with the controller and used for measuring the outflow temperature of the water in the waterway;

The controller is used to open the pressure relief condenser valve when the water heater supplies hot water and the outflow temperature measured by the outflow water temperature sensor is higher than the set pressure relief temperature.

Wherein, the heating condenser valve and the pressure relief condenser valve are solenoid valves.

As an alternative solution, for the judgment of compressor running time in some cases, the comparison of preset time covers the intrinsic value, in other words, if the continuous compressor running time interval exceeds or equals to the preset value, close the compressor; if not, close the heating condenser valve and open the pressure relief condenser valve, so as to make the compressor continue running till the preset time before closing it.

Different from thermal storage heat pump water heaters, which are in static heating most of the time and thus cause high condensation temperature (or condensation pressure) of the heat pump system during its operation most of the time, the tankless water heater of the present invention takes dynamic heating, during which the condensation temperature (or condensation pressure) is relatively low, for which the heat pump efficiency is higher, the heat pump system will not operate much bad and the compressor can work longer.

In the moment of compressor opening, most of the refrigerator oil in the compressor may be discharged with the refrigerant out of the compressor, and in case of shutdown when the refrigerant system has not completed multiple cycles, the refrigerator oil will stay in the system pipeline as well as the condenser and the evaporator, in which case, when the compressor is opened next time, the oil in the compressor will be less, which may reduce the lubrication action for the compressor, thus affecting the service life of the compressor if the compressor is started up like this for a long time.

In the moment of compressor opening, most of the refrigerator oil in the compressor may be discharged with the refrigerant out of the compressor, and in case of shutdown when the refrigerant system has not completed multiple cycles, the refrigerator oil will stay in the system pipeline as well as the condenser and the evaporator, in which case, when the compressor is opened next time, the oil in the compressor will be less, which may reduces the lubrication action for the compressor, thus affecting the service life of the compressor if the compressor is started up like this for a long time. To solve the oil return problem caused by short-time operation of the unit, we prolong the unit's operation time via pressure relief condenser branch, so as to achieve the purpose of oil return.

The control connection of the present invention refers to the controller and the controlled component being in such connection relation: the control signal given by the controller can make the controlled component complete the action corresponding to the control signal. The mechanical or electrical connection relation can be direct or indirect, for instance, the controller can directly send electrical signals to control the opening and closing of the solenoid valve, but the controller can also control the air pump first by electrical signals, then the air pump controls the opening and closing of the pneumatic valve via air pressure.

When water heaters are being used, problems of opening or closing waterway and frequently switching of the water-passing state often exist, in which aspect, different from thermal storage water heater, the tankless water heater has no large-capacity water storage device, thus the heating device usually needs to be opened or closed frequently, while for the air-energy water heater providing heat sources through heat pump circulation, the refrigerant fluid in the heat pump circulation loop after shutdown requires certain time to achieve pressure balance, and if the pressure of the refrigerant fluid in the loop is not balanced, the compressor start-up command will be given, thus causing two consequences: 1) the compressor cannot be opened in time, which may lead the heating capacity of the whole machine to lag behind and disable the water temperature from reaching the preset value; 2) the compressor can be opened, and since high and low pressures of the compressor are not fully balanced, the compressor's service life may be affected. Of the tankless water heater of the present invention, a heating condenser and a pressure relief condenser, on which valves are provided respectively to control the connection state of the two branches, are set in series at the condenser part of the heat pump circulation loop. When the water heater supplies hot water normally, the circuit where the heating condenser lies is opened to make high-temperature high-pressure refrigerant condensed, so as to heat the waterway heating part. When the continuous compressor operation time is insufficient and hot water is not required, close the circuit where the heating condenser lies to stop the heating condenser's heating to the waterway heating part, meanwhile, open the pressure relief condenser to enable the heat pump circulation to continue until the preset working time before closing the compressor, which avoids a compressor emergency shutdown's damage to the equipment.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is the schematic view of the structure module of the embodiment of the present invention;

FIG. 2 is the schematic view of the structure of the embodiment of the present invention;

FIG. 3 is the schematic view of the structure of the evaporator and the pressure relief condenser connected via radiator of the embodiment of the present invention.

BRIEF DESCRIPTION OF THE REFERENCE NUMERALS OF MAJOR COMPONENTS

6. water inlet; 3. heating part; 5. water outlet; 1. compressor; 7. throttle device; 18. evaporator; 181. evaporator joint; 182. evaporator joint; 4. heating condenser; 19. pressure relief condenser; 191. pressure relief condenser joint; 192. pressure relief condenser joint; 2. heating condenser valve; 14. pressure relief condenser valve; 204. inlet valve; 203. outlet valve; 201. sprinkler; 202. bathtub; 10. filter; 11. expansion valve; 17. pressure relief capillary; 9. gas-liquid separator; 15. motor; 16. fan blades; 30. fins; 40. pipeline from the heating condenser; 50. coil.

DETAILED DESCRIPTION OF THE INVENTION

To describe the technical contents, structural features and realization purposes and effects more clearly, the embodiments will be taken to detail the present invention in combination with the drawings.

As shown in FIG. 1 and FIG. 2, the present embodiment provides a tankless water heater, including a controller, a waterway and a heat pump circulation loop;

In the water-flowing direction, the waterway successively includes: an inlet 6, a heating part 3 and an outlet 5;

The heat pump circulation loop successively includes: a compressor 1, an evaporator 18, a condenser and a throttle device 7, wherein the compressor is in control connection with the controller, and the condenser includes a heating condenser 4 and a pressure relief condenser 19, wherein the heating condenser 4 is in heat conduction contact with the heating part in the waterway and is set in series with the pressure relief condenser 19 in the heat pump circulation loop, besides, a heating condenser valve 2 is set in the branch where the heating condenser lies and a pressure relief condenser valve 14 in that where the pressure relief condenser stands, wherein the heating condenser valve 2 and the pressure relief condenser valve 14 are in control connection with the controller;

In heat conduction contact with the heating part, the heating condenser can be put in the heating part to exchange heat with the water in the heating part via heat conduction; or attached to the heating part pipeline or the outer wall of the capacity to exchange heat with the heat conduction of the outer wall depending on the pipeline. Either plate-type or coil-type heat exchanger is acceptable.

In the embodiment as shown in FIG. 2, the water inlet 6 of the waterway is connected with the inlet valve 204 and the water outlet with the outlet valve 203, wherein the outlet valve can be connected with external water-use components such as the sprinkler 201 and the bathtub 202.

The heat pump circulation loop starts from the compressor and falls into two parallel condenser branches: the branch where the heating condenser lies and the branch where the pressure relief condenser stands, specifically:

The branch where the heating condenser lies successively includes the heating condenser valve 2, the heating condenser 4, the filter 10 and the expansion valve 11;

The branch where the pressure relief condenser stands successively includes the pressure relief condenser valve 14, the pressure relief condenser 19 and the pressure relief capillary 17;

After meeting each other, the two branches are connected with the evaporator 18 and than with the compressor 1 via the gas-liquid separator 9.

The throttle device 7 of the above embodiment includes the expansion valve 11 and the pressure relief capillary 17.

The controller is used for controlling the opening and closing of the compressor, the heating condenser valve and the pressure relief condenser valve, specifically, when the water heater supplies hot water, keeping the heating condenser valve open; when requiring the closing of the compressor, judging whether the compressor running time is over the preset time, and if so, close the compressor; if not, close the heating condenser valve and open the pressure relief condenser valve, so as to enable the compressor to run till the preset time before closing it.

In some embodiments, the tankless water heater includes a fan, wherein the evaporator and the pressure relief condenser are located in the same air duct formed by the fan. As shown in FIG. 2, the fan consists of a motor 15 and fan blades 16, wherein the airflow blown by the fan blades passes through the evaporator 18 and the pressure relief condenser 19 in succession, and when the pressure relief condenser 19 works, due to temperature drop when passing through the evaporator, the low-temperature airflow's going through the pressure relief condenser will greatly improve the heat dissipation effect of the pressure relief condenser, which enhances the circulation efficiency of the whole heat engine, thus contributing to the improvement of energy utilization and the relief of equipment load. Certainly, in some embodiments, the airflow can also pass by the pressure relief condenser first for a temperature rise and to heat the evaporator by making use of high-temperature airflow to improve the evaporation effect of the evaporator and enhance equipment efficiency.

In some embodiments, the evaporator and the pressure relief condenser are in wholly expanded connection through a copper tube-fin. Thus, when the pressure relief condenser works, the heat generated will be conducted to the evaporator by means of the temperature difference on the fins, and the high-efficiency heat flow between the two components will greatly increase the heat engine efficiency, which is also beneficial to the entire equipment maintenance. For instance, in the embodiment shown in FIG. 3, the pressure relief condenser joint 191 is connected with the compressor exhaust pipe and the evaporator joint 181 with the compressor gas-liquid separator, wherein the evaporator joint 182 and the pressure relief condenser joint 192 are respectively connected with the pipeline from the heating condenser 40, wherein the pressure relief condenser joint 192 is further connected to the pressure relief capillary 17 and the filter 10, and between the two pressure relief condenser joints, the coils 50 are connected, similarly, the coils 50 are also linked between the two evaporator joints, besides, the coils 50 are in expanded connection by fins 30, which is convenient for heat conduction. If the dissipating fin heat is in combination with the fan, the effect will be more satisfactory.

In some embodiments, the tankless water heater further includes an outflow water temperature sensor 7, which is connected with the controller and used for measuring the outflow temperature of the water in the waterway;

The controller is used to open the pressure relief condenser valve when the water heater supplies hot water and the outflow temperature measured by the outflow water temperature sensor is higher than the set pressure relief temperature.

Because in case of considerable water flow fluctuation, such as unstable inflow temperature, over-temperature phenomenon may occur after inflow temperature rise, at this point, it is acceptable to judge according to the outflow temperature, that is, open the pressure relief condenser valve to make the pressure relief condenser operate, besides, unloading part of the heat pump capacity will be also in favour of relieving the compressor operation load to achieve energy consumption reduction. Meanwhile, the situation where the compressor has to be closed due to over high water temperature but opened again quickly after water temperature fluctuation can be avoided, thus averting compressor's frequent opening and closing, which may have adverse effect over the unit.

The description above is only to illustrate the embodiments but not to limit the patent scope of the present invention. Any equivalent structure or procedure substitution based on the Specification and the Drawings of the present invention, or direct or indirect application in other related technical fields shall be all within the protection scope of the present invention. 

What is claimed is:
 1. A tankless water heater, characterized in that it includes a controller, a waterway, and a heat pump circulation loop; the waterway, in the water-flowing direction, successively includes: an inlet, a heating part and an outlet; The heat pump circulation loop successively includes: a compressor, an evaporator, a condenser and a throttle device, wherein the compressor is in control connection with the controller, and the condenser includes a heating condenser and a pressure relief condenser, wherein the heating condenser is in heat conduction contact with the heating part in the waterway and is set in series with the pressure relief condenser in the heat pump circulation loop, besides, a heating condenser valve is set in the branch where the heating condenser lies and a pressure relief condenser valve in that where the pressure relief condenser stands, wherein the heating condenser valve and the pressure relief condenser valve are in control connection with the controller; The controller is used for controlling the opening and closing of the compressor, the heating condenser valve and the pressure relief condenser valve, specifically, when the water heater supplies hot water, keeping the heating condenser valve open; when requiring the closing of the compressor, judging whether the compressor running time is over the preset time, and if so, close the compressor; if not, close the heating condenser valve and open the pressure relief condenser valve, so as to enable the compressor to run till the preset time before closing it.
 2. The tankless water heater according to claim 1, characterized in that the tankless water heater includes a fan, wherein the evaporator and the pressure relief condenser are located in the same air duct formed by the fan.
 3. The tankless water heater according to claim 1, characterized in that the evaporator and the pressure relief condenser are in heat conduction connection via radiator.
 4. The tankless water heater according to any one of claims 1 to 3, characterized in that: the tankless water heater further includes an outflow water temperature sensor, which is connected with the controller and used for measuring the outflow temperature of the water in the waterway; the controller is used to open the pressure relief condenser valve when the water heater supplies hot water and the outflow temperature measured by the outflow water temperature sensor is higher than the set pressure relief temperature.
 5. The tankless water heater according to any one of claims 1 to 3, characterized in that the heating condenser valve and the pressure relief condenser valve are solenoid valves.
 6. A tankless water heater, characterized in that, including a controller, a waterway and a heat pump circulation loop; In the water-flowing direction, the waterway successively includes: an inlet, a heating part and an outlet; The heat pump circulation loop successively includes: a compressor, an evaporator, a condenser and a throttle device, wherein the compressor is in control connection with the controller, and the condenser includes a heating condenser and a pressure relief condenser, wherein the heating condenser is in heat conduction contact with the heating part in the waterway and is set in series with the pressure relief condenser in the heat pump circulation loop, besides, a heating condenser valve is set in the branch where the heating condenser lies and a pressure relief condenser valve in that where the pressure relief condenser stands, wherein the heating condenser valve and the pressure relief condenser valve are in control connection with the controller; The controller is used for controlling the opening and closing of the compressor, the heating condenser valve and the pressure relief condenser valve, specifically, when the water heater supplies hot water, keeping the heating condenser valve open; when requiring the closing of the compressor, judging whether the compressor running time is over the preset time, and if so, close the compressor; if not, close the heating condenser valve and open the pressure relief condenser valve, so as to enable the compressor to run till the preset time before closing it.
 7. The tankless water heater according to claim 6, characterized in that the tankless water heater includes a fan, wherein the evaporator and the pressure relief condenser are located in the same air duct formed by the fan.
 8. The tankless water heater according to claim 6, characterized in that the evaporator and the pressure relief condenser are in heat conduction connection via radiator.
 9. The tankless water heater according to any one of claims 6 to 8, characterized in that the tankless water heater further includes an outflow water temperature sensor, which is connected with the controller and used for measuring the outflow temperature of the water in the waterway; The controller is used to open the pressure relief condenser valve when the water heater supplies hot water and the outflow temperature measured by the outflow water temperature sensor is higher than the set pressure relief temperature.
 10. The tankless water heater according to any one of claims 6 to 8, characterized in that the heating condenser valve and the pressure relief condenser valve are solenoid valves. 